Good news! Traced the wire from the firewall all the way to the three wires that were connected to the disconnected ballast. Although there have been a few comments stating that the correct wire is white with a blue spiral, my car’s wiring has a white wire with a blue plastic collar where it exits each connector, no blue stripes. Tach now works but accuracy remains to be tested. An inline resister may be required. Thanks to all.
Jetlock. Just observed question. Has the problem been resolved???. If not try CRC on the shaft above the plastic plate. Wait a few minutes then gently pry up using a screw driver in the provided slots. It is just friction holding the plate to the shaft. P.S. I had original opus, and replaced with Petronix. Easy to feet the end end result is tremendous.
DaveM
S3 NZ.